MATLAB: How to call a get.properties method in a script

calssdefget.propertiesoop

Hi, I'm trying to use the get.propertie function on a private propertie.

classdef t_point2D

     properties (Access = private)
        X;
        Y; 
    end
    methods
        %Defenir le constructeur
        function point2D = t_point2D(X,Y)
            if nargin == 0
                point2D.X =0;
                point2D.Y=0;
            elseif nargin == 1 || nargin >2
                fprintf('Error');
            else
                point2D.X = X;
                point2D.Y = Y;
            end
        end
        %accesseurs 
        function X = get.X(point2D)
         X = point2D.X;
        end

Then, I try to call it in a script :

 point1 =t_point2D(2,8);
 XX = get.X(point1);

I get the following error message : Undefined variable "get" or class "get.X".

Error in test (line 4) XX = get.X(point1);

I supposed I'm not calling the method the right way? I can't find the doc on how to call a get.prop function.

Best Answer

You have two problems:

1. You're using the wrong syntax for accessing properties. Regardless of the syntax used to define the property accessor, the way to access the property is just obj.propname, so:

XX = point1.X

2. The above won't help because the whole point of a private property is that it can't be accessed from outside the class. So if you want access to the X property you need to make it public (at least for GetAccess)

Note: As shown, your accessor function does not enable anything that wasn't already available without it. So if all you do is make X public, you may as well remove that function.

The following may be what you're after:

classdef  Point2D
   properties (GetAccess = public, SetAcces = private)
      X;
      Y;
   end
   methods
      function this = Point2D(X, Y)   %constructeur
         %body of constructor
      end
      %No need for accessor, you can already do Point2D.X
   end
end

Related Solutions

MATLAB: Property validation in subclass

Note: I would recommeng giving a name other than set to your property. That name is already overloaded enough by matlab.

You can create a property validation function in the class that define the property using the syntax (for handle classes):

function set.propertyname(object, valuetoset)
    %validation code
end

with your property name this would be

function set.set(this, value)     %See why you should rename the property?
   if ~strcmp(class(value), somevalidclass)
        error('invalid class supplied to set');
   end
   this.set = value;
end

However, as I said, this property set method must be implemented in the class that defines the property, that is your base class, not the derived class. The workaround is from the set method to call another method that does the validation and is overridden by the derived class:

classdef SimpleList < handle
    properties
        set;
    end
      methods
          function set.set(this, value)
              isok = this.validateset(value);  
              if ~isok
                 error('invalid type of variable for set property)
              end
              this.set = value;  %DO NOT set the value is a subfunction or you'll get infinite recursion
          end
      end
      methods (Access = protected)
          function isok = validateset(this, value)
             isok = true;
          end
      end
  end
classdef ObjList < SimpleList
    methods (Access = protected)
        function isok = validateset(this, value)
           isok = strcmp(class(value), 'double');
        end
    end
end

MATLAB: How to change a 1×10 matrix into two 1×5 matrices.

You typed [x; y; x; y; x; y; x; y; x; y;], which will result in a 10x1 matrix instead of 1x10. In any case, you can use reshape(), for example

>> x = [1 2 1 2 1 2 1 2 1 2]
x =
     1     2     1     2     1     2     1     2     1     2
>> y = reshape(x, 2, [])
y =
     1     1     1     1     1
     2     2     2     2     2

Best Answer

Related Solutions

MATLAB: Property validation in subclass

MATLAB: How to change a 1×10 matrix into two 1×5 matrices.

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